1. Field of the Invention
The present invention relates to a coupling for the connection of a tool holder to an interchangeable tool head in a machine tool in which the tool head is provided with a preferably at least partially conical receiving pin and an annular contact collar forming a supporting face, the receiving pin and the contact collar cooperating with a corresponding receiving bore and a counterface on the tool holder which cooperates with the contact collar. The tool holder and tool head are arrested by means of clamping elements which are actuated by means of a clamping device so that the contact collar of the tool head rests firmly against the counterface of the tool holder.
2. Description of the Prior Art
The task of exchanging tools as quickly as possible in machine tools has become increasingly significant with the increasing desire for cost-effective operation. Various coupling systems have been proposed to solve this problem. In these coupling systems, the releasable coupling between an exchangeable tool head and a tool holder resides in the fact that the tool holder has a receiving pin onto which a corresponding bore in the tool head is placed. After being placed in the tool holder, the tool head is arrested by means of suitable clamping elements which are usually actuated by a pull rod that is displaceable axially with respect to the tool holder.
The receiving pin of the tool head is generally cylindrical, sometimes conical. The conical configuration has the advantage that the receiving pin of the tool head can easily be inserted into the corresponding receiving bore of the tool holder. However, the self-inhibition of conical connections is a drawback for the quick exchange of tool heads. It has also been found that if a conical receiving connection is used, the high rigidity and accurate positioning necessary in tools subject to high stresses can be realized only if, in addition to the conical radial guidance which is thus without play, there also exists an axial contact between tool head and basic holder. The simultaneous fixing of the tool head by means of a conical connection and planar contact has been possible in the past only in that deformable intermediate pieces were provided between the tool head and the receptacle in the basic holder or in that, during closing of the coupling system, deformation of the material of the receiving elements themselves, i.e. at the receiving pin and/or in the receiving bore, was permissible. To realize such deformation, however, extremely high tension and ejection forces are required which the actuating device must be able to handle. The components of this actuating device must be dimensioned accordingly and, since they are difficult to accommodate, require much space.